The objective of this study is to assess the relationship between cardiac output as measured by thermodilution method with cold dextrose solution and dynamic changes in peripheral oxygen saturation monitored via a finger pulse oximeter after three breathes of hyperbaric oxygen. The indicator dilution method has been used consistently over the years to measure cardiac output. Thermodilution has become the most widely used method because it does not involve arterial access, neither does it interfere with oxygen carrying capacity and furthermore it is free of indicator buildup problems. However, it does require central venous access. Our goal is to establish a method which is non-invasive, safe, reasonably accurate and can easily be performed in a regular clinical setting.